Circulator with connecting arms designed in accordance with the MIC technique

ABSTRACT

A circulator includes connecting arms designed in accordance with the MIC technique which merged to form a branch, wherein a disc constructed of gyromagnetic material is arranged in the branching zone and is subjected to a constant magnetic field produced by a permanent magnet. The disc is surrounded by a plate constructed of dielectric material. On one side of the plate the connecting arms for the branch are provided and on the other side of the plate a continuous metallization is applied. An insert consisting of dielectric material is disposed between the line branch and the disc of gyromagnetic material, the dielectric constant of the insert being smaller than the dielectric constant of the gyromagnetic material.

United States Patent Deutsch Nov. 25, 1975 [75] Inventor:

[73] Assignee: Siemens Aktiengesellschaft, Berlin and Munich, Germany[22] Filed: Oct. 24, I973 [21] Appl. No: 409,251

[44] Published under the Trial Voluntary Protest Program on January 28,1975 as document no.

Josef Deutsch, Munich, Germany [30] Foreign Application Priority DataOct. 30 I972 Germany r. 2253l75 [52] US. Cl. 333/11; 333/84 M [51] Int.Cl. HOIP 1/38 [58] Field of Search 333/l.l

[56] References Cited UNITED STATES PATENTS 3,l65,7ll l/l965 Drumhelleret al 333/l.l

3,324,418 6/1967 Caswell .r 333/1] 3,456,213 7/1969 Hershenov 3,662,29l5/1972 Cotter 333/l.l

Primary ExaminerPaul L. Gensler Attorney, Agent or Firm-Hill, Gross.Simpson, Van Santen, Steadman, Chiara & Simpson [57] ABSTRACT Acirculator includes connecting arms designed in ac cordance with the MICtechnique which merged to form a branch, wherein a disc constructed ofgyro magnetic material is arranged in the branching zone and issubjected to a constant magnetic field produced by a permanent magnet,The disc is surrounded by a plate constructed of dielectric material. Onone side of the plate the connecting arms for the branch are pro videdand on the other side of the plate a continuous metallization isapplied. An insert consisting of dielec tric material is disposedbetween the line branch and the disc of gyromagnetic material thedielectric con stant of the insert being smaller than the dielectricconstant of the gyromagnetic material.

2 Claims, 1 Drawing Figure CIRCULATOR WITH CONNECTING ARMS DESIGNED INACCODANCE WITH THE MIC TECHNIQUE BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to a circulator having connectorarms constructed in accordance with the microwave integrated circuit(MIC) technique which are merged to form a branch circuit, and morespecifically to such a circulator which has a disc of gyromagneticmaterial arranged in the branching zone and subjected to the influenceof a constant magnetic field produced by a permanent magnet andsurrounded by a layer of dielectric material. The connecting arms of thebranching circuit are carried on one side of the disc while a continuousmetallization is provided on the other side of the disc.

2. Description of the Prior Art In the construction of microwavecircuits circulators have found a wide field of application, as is wellknown, because the microwave energy fed into one arm is passed on almostcompletely to the other arm which follows in the direction of rotationof the circulator, while one or more additional connecting arms are decoupled as opposed to the connecting arms. A particular well knownexemplary embodiment of such branching circulators are constructed sothat a three-terminal line branching is provided. In the branching zoneitself at least one ferrite or garnet disc is concentrically arranged.In addition, it is important for the electrical op eration that theferrite is subject to a constant magnetic field whose strength as wellas the shape and type of the ferrite is determined for the operatingfrequency range of the circulator. For obtaining a method ofconstruction wherein the circulator is as compact as possible, branchingcirculators are realized in accordance with so called MIC method ofconstruction, i.e., the line branching or the individual connecting armsrespectively, are designed as an integrated microwave circuit. The threeconnecting arms, and if required also the line branching, are appliedonto a plate of dielectric material, such as a ceramic substrate forexample, according to the known methods of printing or etchingtechniques. The opposite side of this plate is generally provided with acontinuous metallization. A recess is formed in the plate of dielectricmaterial in the form of a circular bore for example, and a discconsisting of gyromagnetic material is fitted into the recess. Knownferrite and garnet materials are appropriate for use as gyromagneticmaterials. A permanent magnet is employed for creating the constantmagnetic field as is already known for example from the German publishedapplication 2,042,]46. The adaptation and the band width of suchcirculators is determined essentially by the difference between theinput resistance of the circulators at the ferrite or the garnet,respectively, and the microwave resistance of the terminal lines. In thecase of the prior art arrangements, the input resistance lies, forexample, at approximately to ohms, while the wave resistance at theterminal lines amounts generally to approximately 50 ohms. In order toimprove the adaptation and its band width, so called M4 terminationlines are connected for example between the terminal lines and theintermediate circulator input. In spite of this measure, the bank widthwhich can be achieved and exploited with such circulators is insuffi- 2cient for many purposes of application since, as it is well known, theadaptation and the decoupling of the individual circulator arms isdifficult because of the direct links therebetween.

SUMMARY OF THE INVENTION A principle object of the present invention isto eliminate the above-mentioned difficulties as much as possible and toprovide a circulator construction which is O realized in accordance withMIC techniques, and more specifically to the provision of suchcirculators for obtaining large exploitable frequency band widths andsmall input reflection factors without disadvantageously influencing theremaining electrical features, such as the transit damping of thecirculator for example.

Starting from a circulator having connecting arms constructed inaccordance with the MIC technique and merged to form a line branching,wherein a disc of gyromagnetic material is arranged in the branchingzone and subjected to a constant magnetic field produced by a permanentmagnet and surrounded by a plate of dielectric material, the plate beingprovided with the connecting arms on one side thereof and a continuousmetallized layer on the other side thereof, the above object is achievedaccording to the invention in that an insert consisting of dielectricmaterial is positioned between the line branches and the disc ofgyromagnetic material, the dielectric constant of the insert beingsmaller than the dielectric constant of the gyromagnetic material.

The invention is based on the realization that an improvement of theadaptation and an enlargement of the band width can be achieved by meansof an increase in the input resistance of the gyromagnetic material.This increase of the input resistance can be attained by an artificialdecrease of the dielectric constant of the active portion, namely thegyromagnetic material. The dielectric constant of the ferrite or garnet,respectively, is prescribed particularly by their crystalline structureand their chemical compound. The input resistance can be increased by ashifting of the dielectric constant, and the exploitable band width canbe enlarged thereby, as is shown, by approximately 50 to [00 percent.

BRIEF DESCRIPTION OF THE DRAWING Other objects, features and advantagesof the invention, its organization, construction and operation will bebest understood from the following detailed description taken inconjunction with the accompanying drawing, on which the single FIGURE isa sectional elevation of a circulator constructed in accordance with theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing, aplate 1 of dielectric material, for example a ceramic material, isprovided as a substrate. The connecting arms of the circulator areapplied to the substrate in the form of conductor paths 4 on the uppersurface of the plate 1 in a manner well known in the art. The connectingarms are merged to form a line branching circuit. On the opposite orbottom side of the substrate 1 a continuous metallized layer 3 isprovided. A recess, e.g. a circular bore, is provided in the plate 1 anda disc 6 of gyromagnetic material is inserted into the recess in such away that it completely fills the space thereof. As gyromagnetic mate- 3rial, one may consider the utilization of known ferrite or garnetmaterials. ln order to create a constant magnetic field, a permanentmagnet is employed which is located on the upper surface ofthedielectric plate 1, that is on the side which carries the conductorpaths 4.

In an advantageous construction, as is illustrated in the drawing, apair of pole pieces 2 and 2 are provided for the permanent magnet 10.The pole pieces 2, 2 are arranged facing one another and are disposedconcen trically with respect to the ferrite or garnet disc 6. The polepieces 2 and 2 consist ofa magnetic material such as iron and areinterconnected by a magnetically conductive member 8. The pole piecesinclude. at least on the side which faces the conductor paths, a thinlayer of electrically highly conductive material, for example, a silverlayer. As it is illustrated in the drawing by the solder layers 5, theupper pole piece 2 can be connected in a highly conductive or lowresistance manner with the conductor paths 4 and the lower pole piece 2can enjoy the same type of connection with the continuous metallic layer3. Thus, the upper pole piece 2 acts as a line branching connection andthe lower pole piece 2 functions as a connection of the continuousmetallization 3. Both pole pieces operate to feed and render theconstant magnetic field homogeneous adjacent to a gyromagnetic material6.

The previously mentioned shifting of the dielectric constant of thegyromagnetic material 6 can be provided in such a way that an insert 7is inserted between the pole piece 2 forming the line branching and thedisc 6, which insert 7 consists of a dielectric material having adielectric constant which is smaller than that of the gyromagneticmaterial 6. The thickness of the insert 7 depends on the dielectricconstant of the material employed and on the dielectric constant of thedisc 6. A material which has proven to be particularly useful for theinsert 7 is a material which is sold under the trademark Teflon, whoserelative dielectric constant is approximately 2.

If necessary, a further increase of the input resistance of thecirculator can be provided by the provision of an additional insert 7'between the pole shoe 2' and the continuous metallization 3 and the disc6 of gyromagnetic material. The upper insert 7 may be omitted completelyand only the lower insert 7' be utilized.

An advantageous development of the invention is illustrated in thedrawing wherein the permanent magnet 10 is arranged on the side of theceramic substrate 1 which carries the conductor paths 4. The constantmagnetic field can therefore be closed by way ofa magnetic yoke 8, alsoconsisting of magnetic material, whereby stray fields of the permanentmagnet 10 which would otherwise cause interference are no longereffective. For the construction of larger circuit arrangements, thecirculator can be arranged in this manner without diffi culties in closeproximity to magnetically and electrically conductive parts, such asframes, braces or the 4 like, or close to magnetic elements, such astraveling wave tubes for example, without resulting in interferingreactions between the individual elements involved.

Apart from the previously mentioned increase of the input resistance ofthe circulator and the considerable increase in the useable band widthby 50 to percent, and the further resulting decrease of the inputreflection factor, it is additionally achieved in the describedintegrated circulator the M4 transformation line which are possiblyrequired can be more highly resistant and therefore narrower and asmaller part of interfering longitudinal components of the microwavefield is stimulated. Since an increase of the diameter of the ferrite orgarnet is necessary in general because of the shifting of the dielectricconstant of the gyromagnetic material, such a construction isparticularly suitable for frequencies in the X band because the normallysmall diameter of the ferrite can be increased.

Although I have described my invention by reference to a particularillustrative embodiment thereof, many changes and modificatins of theinvention may become apparent to those skilled in the art withoutdeparting from the spirit and scope of the invention. I therefore intendto include within the patent warranted hereon all such changes andmodifications as may reasonably and properly be included within thescope of my contribution to the art.

I claim:

1. A circulator comprising a disc of gyromagnetic material, connectingarms for forming a branch line, said disc disposed in the zone ofbranching, said connecting arms constructed in accordance with microwaveintegrated circuit technique and comprising a plate of dielectricmaterial surrounding said gyromagnetic disc, a continuous metal layercarried on a first side of said dielectric plate, separate connectingarm metal layers carried on the second side of said dielectric plate, apermanent magnet adjacent said disc on said second side of saiddielectric plate, a first pole piece of magnetic material carrying ahighly conductive metal coating disposed between said permanent magnetand said connecting arm layers and electrically connected to saidconnecting arm layers, a second pole piece carrying a highly conductivemetal coating disposed adjacent and electrically connected to saidcontinuous metal layer, a magnet yoke connecting said permanent magnetand said second pole piece, and an insert of dielectric material havinga dielectric constant which is smaller than the dielectric constant ofsaid gyromagnetic disc disposed between said first pole piece and saidgyromagnetic disc.

2. A circulator according to claim 1, comprising a further insert ofdielectric material having a dielectric constant which is smaller thanthe dielectric constant of said gyromagnetic disc disposed between saidsecond pole piece and said gyromagnetic disc.

1. A circulator comprising a disc of gyromagnetic material, connectingarms for forming a branch line, said disc disposed in the zone ofbranching, said connecting arms constructed in accordance with microwaveintegrated circuit technique and comprising a plate of dielectricmaterial surrounding said gyromagnetic disc, a continuous metal layercarried on a first side of said dielectric plate, separate connectingarm metal layers carried on the second side of said dielectric plate, apermanent magnet adjacent said disc on said second side of saiddielectric plate, a first pole piece of magnetic material carrying ahighly conductive metal coating disposed between said permanent magnetand said connecting arm layers and electrically connected to saidconnecting arm layers, a second pole piece carrying a highly conductivemetal coating disposed adjacent and electrically connected to saidcontinuous metal layer, a magnet yoke connecting said permanent magnetand said second pole piece, and an insert of dielectric material havinga dielectric constant which is smaller than the dielectric constant ofsaid gyromagnetic disc disposed between said first pole piece and saidgyromagnetic disc.
 2. A circulator according to claim 1, comprising afurther insert of dielectric material having a dielectric constant whichis smaller than the dielectric constant of said gyromagnetic discdisposed between said second pole piece and said gyromagnetic disc.